The present invention is drawn to a process for regenerating used foundry sand having high oolitic levels and, more particularly, a process as aforesaid wherein the used foundry sand is subjected to magnetic separation by one or more high power magnets for dividing the used foundry sand into a first highly magnetic stream containing a high degree of oolite particles and a second less magnetic stream having a relatively high degree of sand particles.
It is known in the prior art to reclaim used foundry sand to mechanical and/or thermal treatment followed by a separating process which separates the sand granules from the oolith materials. Typical prior art processes are disclosed for example in U.S. Pat. No. 3,312,403 and U.S. Pat. No. 5,163,562. In addition to the known processes disclosed above, German Document DE 36 42 916 discloses a process for reclaiming used foundry sand wherein the foundry sand is subjected sequentially to the steps of screening, annealing, pressure blasting and magnetic separation. The aforesaid process disclosed in the German document is very expensive. In particular, because of the annealing step in the German process, a very high energy is required which adds considerably to the expense of the process.
In order to overcome the problems associated with known sand recovery processes, it is the object of the present invention to provide a process which allows for the separation of new sand particles which are easily regenerable from those particles which are difficult to regenerate prior to performing the actual mechanical and or thermal regeneration steps.